sepuri sai krishna created FLINK-41412:
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Summary: Support IF EXISTS for ALTER VIEW, DATABASE, CATALOG and
MATERIALIZED TABLE
Key: FLINK-41412
URL: https://issues.apache.org/jira/browse/FLINK-41412
Project: Flink
Issue Type: Improvement
Components: Table SQL / API
Affects Versions: 2.4.0
Reporter: sepuri sai krishna
Every {{DROP}} statement takes {{IF EXISTS}}. {{ALTER}} takes it for three of
the seven object
kinds.
||object||documented DROP||documented ALTER||
|{{TABLE}}|{{DROP [TEMPORARY] TABLE [IF EXISTS] ...}}|{{ALTER TABLE [IF EXISTS]
table_name ...}}|
|{{FUNCTION}}|{{DROP [TEMPORARY\|TEMPORARY SYSTEM] FUNCTION [IF EXISTS]
...}}|{{ALTER [TEMPORARY\|TEMPORARY SYSTEM] FUNCTION [IF EXISTS] ...}}|
|{{MODEL}}|{{DROP [TEMPORARY] MODEL [IF EXISTS] ...}}|{{ALTER MODEL [IF EXISTS]
...}}|
|{{VIEW}}|{{DROP [TEMPORARY] VIEW [IF EXISTS] ...}}|{{ALTER VIEW
[catalog_name.][db_name.]view_name ...}}|
|{{DATABASE}}|{{DROP DATABASE [IF EXISTS] ...}}|{{ALTER DATABASE
[catalog_name.]db_name SET (key1=val1, key2=val2, ...)}}|
|{{CATALOG}}|{{DROP CATALOG [IF EXISTS] catalog_name}}|{{ALTER CATALOG
catalog_name SET (key1=val1, ...)}}|
|{{MATERIALIZED TABLE}}|{{DROP MATERIALIZED TABLE [IF EXISTS] ...}}|{{ALTER
MATERIALIZED TABLE [catalog_name.][db_name.]table_name ...}}|
The four missing forms are parse errors on master:
{code:sql}
ALTER VIEW IF EXISTS v RENAME TO v2;
ALTER VIEW IF EXISTS v AS SELECT 1;
ALTER DATABASE IF EXISTS d SET ('k' = 'v');
ALTER CATALOG IF EXISTS c SET ('k' = 'v');
ALTER MATERIALIZED TABLE IF EXISTS mt SUSPEND;
{code}
{code}
Encountered "EXISTS" at line 1, column 15. Was expecting one of: "AS" ...
"RENAME" ... "." ...
Encountered "EXISTS" at line 1, column 19. Was expecting one of: "SET" ... "."
...
Encountered "EXISTS" at line 1, column 18. Was expecting one of: "RESET" ...
"SET" ... "COMMENT" ...
Encountered "EXISTS" at line 1, column 29. Was expecting one of: "ADD" ... "AS"
... "DROP" ...
{code}
Without the guard the statement fails on a missing object, for example
{{ALTER MATERIALIZED TABLE mt SUSPEND}} gives
{{Cannot find table '`default_catalog`.`default_database`.`mt`'}}.
The motivation is the one FLINK-41363 gives for columns: re-running a SQL
script should not fail
on the statements that have already been applied. {{ALTER TABLE IF EXISTS}}
gives tables that
property, so the same script becomes order dependent as soon as it touches a
view, a database, a
catalog or a materialized table.
Three of the four already have the capability underneath, so the gap is in what
SQL can express.
{{Catalog#alterDatabase}}, {{Catalog#renameTable}} and
{{CatalogManager#alterTable}} all take an
{{ignoreIfNotExists}} flag, and the operations pass a literal {{false}}:
{{AlterDatabaseOperation}}, {{AlterViewAsOperation}},
{{AlterViewRenameOperation}} and
{{AlterMaterializedTableChangeOperation}}. {{CatalogManager#alterCatalog}} has
no such
parameter, so {{CATALOG}} needs more than the grammar and may be worth
splitting out.
Checked on master, built from source, JDK 17.
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